The present invention relates to a novel fluid product dispenser, having a manually operated piston pump aspirator, within which fluid product to be dispensed is kept free from contaminating affects of air and in readiness for dispensing regardless of the attitude in which the dispenser is held.
More specifically, this invention relates to an improved non-venting aspirator dispensing system having a collapsible bag, such as disclosed in Applicant's co-pending application Ser. No. 337,151, containing dispensable fluid product and closed by a pressure actuated elastomeric valve that opens under the influence of outwards force indirectly exerted thereon by atmospheric pressure whenever a lower than atmospheric pressure exists on the outwards side of the valve.
According to the invention, the bag progressively collapses as the product is aspirated therefrom and it remains in its collapsed state, keeping the product in dispensing readiness communication with the valve, between dispensing operations. In a closed state, the valve blocks back flow of air into the bag and thereby cooperates with atmospheric pressure acting on the exterior of the bag to hold the bag in a collapsed state whereas the product is in dispensing readiness communication with the valve. Dispensing can take place with the dispensing system held in any attitude.
Heretofore piston pump fluid dispensers, such as hand actuated trigger and finger depressible push button piston pump spray apparatus, have required a venting passage from atmosphere into the interior of the fluid product container in order for fluid to be withdrawn. An air space exists above the fluid, and a dip tube is needed to reach fluid at the lower most region of the fluid container.
Thus, existing dispensers are required to be held in a generally upright position, for dispensing, which is often an inconvenience to the user since the dispensers are restricted from upwards and downwards spraying, particularly after a substantial portion of the fluid has been expended.
Piston pump dispensing systems have heretofore required venting in order to function. Piston pumps function by creating, within a pump chamber, a low pressure (less than atmospheric pressure) and atmospheric pressure acting on the surface of the fluid drives the fluid into the pump chamber via the dip tube and a check valve. This function typically takes place on the return or release stroke, of a piston that is within the pump chamber, which follows a dispensing stroke. On the dispensing stroke the check valve closes causing the fluid to be driven from the piston chamber, through a piston chamber outlet, under pressure.
The elastomeric valve of the present invention is provided, in addition to a piston pump check valve, to seal against back flow of air into the collapsible bag via the piston chamber due to low negative pressure effect of gravity acting on fluid within the bag. The check valve, which is generally a loose ball, does not effectively seal against such back flow.
The present invention clearly advances the art of piston pump fluid dispensers and even more, it is a novel non-venting dispensing system that overcomes heretofore adversities of piston pump fluid dispensers. It enables dispensing in any direction, without regard to the dispensing attitude, and it extends product freshness by keeping air away from product awaiting dispensation.